The present invention relates to a retainer for a projectile, and more specifically to a retainer for attaching the rotating band to a projectile.
A spin stabilized projectile developes a spin or rotational motion about its longitudinal axis as the projectile moves through a gun barrel. The projectile carries a rotating band which is a ring-like member attached to the after end of the projectile that protrudes circumferentially from the projectile body so as to engage the gun barrel rifling. During firing of the projectile, the rotating band engraves into the rifling grooves and imparts spin to the projectile. In addition, the rotating band acts as an obturator to prevent leakage of the charge gases between the projectile body and the gun barrel.
During handling and ramming of the projectile in the gun barrel, the rotating band must be retained on the projectile body so as to insure torque transfer from the rifling grooves of the gun barrel to the projectile.
Prior art methods of attaching a rotating band to a projectile include the apparatus disclosed in U.S. Pat. No. 1,007,223 to McNair. The retaining device of McNair utilizes an abutment member to secure the rotating band to the projectile. The abutment member is positioned and secured on the projectile by a split spring ring which cooperates with a groove in the projectile.
Another prior art method of retaining a rotating band on a projectile is disclosed in U.S. Pat. No. 3,744,426, to Butler. The Butler patent discloses the retention of a thermoplastic rotating band by a thermoplastic retaining ring cooperating with a groove in the projectile to abut the rotating band.
The disadvantage of both the Butler and McNair devices is that during high ramming speeds encountered in modern weapons systems the retainers disclosed by Butler and McNair fail to securely attach the rotating bands to the projectiles. At ramming speeds of greater than 21 feet per second the retainer disengages from the projectile groove causing the projectile to move forward in the gun barrel. The forward movement of the projectile can cause the rotating band to lose the gas seal with the rifling grooves thus resulting in a decrease in both projectile velocity and projectile range.
The retainer of the subject invention enables the projectile to withstand ramming speeds up to 26 feet per second without disengagement of the retainer from the projectile groove.